This invention relates to a process for the liquefaction of natural gas by heat exchange initially with a first multicomponent mixture and thereafter with a second multicomponent mixture, each of these mixtures being compressed, at least partially liquefied, and expanded in separate closed refrigeration cycles.
A process for the liquefaction of natural gas is known wherein the natural gas is precooled in heat exchange with a first multicomponent mixture containing several low boiling hydrocarbons and thereupon is liquefied in heat exchange with a second multicomponent mixture different from the first but likewise containing hydrocarbons. Each multicomponent mixture, in a closed cycle, is compressed, liquefied, expanded, and evaporated against the natural gas. The liquefaction of the first multicomponent mixture takes place in heat exchange with cooling water, whereas the second mixture is liquefied in heat exchange with the first mixture ("TRANS. INSTN. CHEM. ENGRS." Vol. 35, 1957, p. 86). A substantial disadvantage of this known process resides in its high energy consumption. Another disadvantage is that because the mixtures are each evaporated in individual heat exchangers, it is also difficult to attain a sufficient temperature stabilization in the individual heat exchangers.